Welcome to Mammoth Hot Springs. Following the links below will take you on
our web-tour of the Mammoth Hot Springs area. To navigate the tour, simply click
'Next Stop' at the bottom of each page. If you prefer you may select features
from the 'List of Stops' or from the 'Interactive
Map'.
Several key ingredients combine to make the Mammoth Hot Springs Terraces: heat, water,
limestone, and a rock fracture system through which hot water can reach the earth's
surface.
Today's geothermal activity is a link to past volcanism. A partially molten magma
chamber, remnant of a cataclysmic volcanic explosion 600,000 years ago in central
Yellowstone, supplies one of the ingredients, heat.
Hot water is the creative force of the terraces. Without it, terrace growth ceases and
color vanishes. The source of the water flowing out of Yellowstone's geothermal features
is rain and snow. Falling high on the slopes in and around Yellowstone, water seeps deep
into the earth. This cold ground water is warmed by heat radiating from the magma chamber
before rising back to the surface.
Hot water must be able to reach the earth's surface in relatively large volumes to
erupt as a geyser or flow as a hot spring. In Yellowstone, many conduits remain from the
collapse of the giant caldera; frequent earthquakes keep this underground
"plumbing" system open. Even though Mammoth lies north of the caldera
ring-fracture system, a fault trending north from Norris Geyser Basin, 21 miles (34 km)
away, may connect Mammoth to the hot water of that system. A system of small fissures
carries water upward to create approximately 50 hot springs in the Mammoth Hot Springs
area.
Another necessary ingredient for terrace growth is the mineral calcium carbonate. Thick
layers of sedimentary limestone, deposited millions of years ago by vast seas, lie beneath
the Mammoth area. As ground water seeps slowly downward and laterally, it comes in contact
with hot gases charged with carbon dioxide rising from the magma chamber. Some carbon
dioxide is readily dissolved in the hot water to form a weak carbonic acid solution. This
hot, acidic solution dissolves great quantities of limestone as it works up through the
rock layers to the surface hot springs. Once exposed to the open air, some of the carbon
dioxide escapes from solution. As this happens, limestone can no longer remain in
solution. A solid mineral reforms and is deposited as the travertine that forms the
terraces.
Terrace features can change rapidly in appearance. Don't be surprised to find that some
of these features look very different if you visit in person.
Mammoth Hot Springs Online Tour
List of Stops | Next Stop
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